Actual sizes
| Nominal | Actual size | Actual size (mm) | End area (actual) | Board feet per linear foot |
|---|---|---|---|---|
| 2x8 | 1-1/2" x 7-1/4" | 38 x 184 mm | 10.88 sq in | 1.333 |
| 2x10 | 1-1/2" x 9-1/4" | 38 x 235 mm | 13.88 sq in | 1.667 |
| 2x12 | 1-1/2" x 11-1/4" | 38 x 286 mm | 16.88 sq in | 2 |
Why wide boards lose 3/4 inch
Under the American Softwood Lumber Standard (PS 20), boards 2 to 6 inches wide are dressed 1/2 inch under their nominal width, and boards 8 inches and wider are dressed 3/4 inch under. That is why a 2x6 is 5-1/2 inches wide but a 2x8 is 7-1/4, not 7-1/2. The thickness stays 1-1/2 inches at every width, and the length is never cut.
Board feet by length
Board feet use the nominal size: thickness × width × length in feet ÷ 12.
| Length | 2x8 | 2x10 | 2x12 |
|---|---|---|---|
| 8 ft | 10.67 | 13.33 | 16.00 |
| 10 ft | 13.33 | 16.67 | 20.00 |
| 12 ft | 16.00 | 20.00 | 24.00 |
| 14 ft | 18.67 | 23.33 | 28.00 |
| 16 ft | 21.33 | 26.67 | 32.00 |
Per linear foot you get 1.333 board feet in a 2x8, 1.667 in a 2x10 and 2 in a 2x12. A 16 ft 2x12 is 2 × 12 × 16 ÷ 12 = 32 board feet.
Which wide board for what
- 2x8: floor joists, rafters and headers in smaller openings, and stair stringers in some designs.
- 2x10 and 2x12: longer joist and rafter spans, headers and deck beams. The right size depends on span, spacing, species, grade and load, so follow your local code tables.
To compare real prices, put each board on a per board foot basis with the lumber cost calculator. The narrower boards sit on the 2x6 page, and the full list is in the lumber dimensions chart.
Frequently asked questions
What is the actual size of a 2x10?
1-1/2 by 9-1/4 inches, or about 38 by 235 mm.
What is the actual size of a 2x12?
1-1/2 by 11-1/4 inches, or about 38 by 286 mm.
What is the actual size of a 2x8?
1-1/2 by 7-1/4 inches, or about 38 by 184 mm.
How many board feet are in a 2x10x12?
20 board feet: 2 x 10 x 12 divided by 12.
Why is a 2x8 7-1/4 inches wide and not 7-1/2?
Lumber 8 inches and wider is dressed 3/4 inch under its nominal width.